storing [NSNull null] values in NSUserDefaults, from JSON serialization, causes unwanted exceptions

Question

I\'ve got an app where I use a JSON based API. As part of JSON, often values are set to \"null\". This may be common:

{\"data\":[\"one\",\"two\",\"three\"]         


        

Answer 1

You can first convert your NSDictionary to NSData, then safely store in NSUserDefaults (since NSNull conforms to NSCoding).

//archive
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:dictionary];
[[NSUserDefaults standardUserDefaults] setObject:data forKey:@"key"];

//unarchive
NSData *newData = [[NSUserDefaults standardUserDefaults] objectForKey:@"key"];
NSDictionary *newDict = [NSKeyedUnarchiver unarchiveObjectWithData:newData];

Edit: Original data object was being referenced instead of newData object.

Answer 2

I've tried some recursive solutions but they tend to be complicated and don't handle mixed type content well. At the simplest level here is a flat example that works well if you have a predictable, flat response to clean.

NSMutableDictionary *dictMutable = [dict mutableCopy];
[dictMutable removeObjectsForKeys:[dict allKeysForObject:[NSNull null]]];